Metabolism
The sum of all energy your body spends — basal needs, digestion, movement — commonly blamed, frequently misunderstood.
Metabolism is total energy expenditure: the basal metabolic rate keeping organs running (usually 60–70% of the total), the thermic cost of digesting food (~10%), deliberate exercise, and NEAT — all the non-exercise movement of a day. Body size and lean mass drive most of the differences between people; the mythical "fast metabolism" is largely being bigger or more muscular, or moving more.
Two facts anchor realistic planning: metabolism adapts downward during weight loss (fewer kilos cost less to run, plus an adaptive extra), and muscle is the lever you control — preserving it through protein and resistance training keeps the engine from shrinking faster than the body. "Boosting metabolism" products, meanwhile, remain decoration.
This glossary entry is general information, not medical advice, and is written to be consistent with FDA prescribing information and primary trial publications as of its last review. Always consult a licensed healthcare provider for personal medical decisions.
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